Hyperemia following aneurysmal subarachnoid hemorrhage: incidence, diagnosis, clinical features, and outcome.

OBJECTIVE: Hyperemia is a known phenomenon after aneurysmal subarachnoid hemorrhage, but only a few reports describe and analyze hyperemia in these patients. This could be the result of diagnostic difficulties in order to identify elevated cerebral blood flow; thus, it seems that hyperemia could be an underdiagnosed clinical state. The aim of the study was to evaluate this phenomenon in comparison with clinical outcome and imaging data in order to describe the frequency of hyperemia after subarachnoid hemorrhage and maybe improve clinical diagnosis.
DESIGN: Retrospective analysis of our cerebral blood flow and transcranial Doppler sonography data bank.
SETTING: . Neurosurgical/Anesthesiological intensive care unit University of Regensburg, Regensburg, Germany. PATIENTS AND PARTICIPANTS: A total of 37 patients were included (24 women and 13 men). All patients suffered from aneurysmal subarachnoid hemorrhage. MEASUREMENTS AND
RESULTS: Standard transcranial Doppler ultrasonography, as well as the Xenon(133) clearance technique for cerebral blood flow measurements, was employed. We observed 37 increases of flow velocities in 37 patients according to Doppler ultrasonography. In order to distinguish between ischemia and hyperemia a Xenon(133) regional cerebral blood flow examination was performed. Global hyperemia was detected in 5 patients (14%). Hyperemia correlated only to favorable outcome ( p=0.01) and fewer ischemic lesions in the computed tomography ( p<0.05).
CONCLUSION: The results indicate that while global hyperemia is a frequent phenomenon that cannot be detected by standard Doppler ultrasonography or clinical examination, hyperemic cerebral blood flow values following aneurysmatic subarachnoid hemorrhage are correlated to favorable outcome.